This invention relates in general to a telecommunication device and in particular to a call screening device for a telephone system.
Various methods and devices have been used to avoid unwanted phone calls. One method telephone subscribers have resorted to is not listing their telephone numbers in published telephone directories. However, with the advent of automatic electronic calling equipment, unlisted telephone numbers do not provide full security against unwanted phone calls.
Another method of avoiding unwanted calls is to use a telephone call screening device. Essentially, these devices are special purpose computers which automatically control incoming telephone calls. A person who places a call to a receiving party's telephone line connected to a call screening device will be requested by the device to enter a security code. If the person calling enters the correct security code, the device will indicate to the receiving party that an incoming call is present to be answered. Anyone who calls the number and fails to enter the correct security code within a preselected time period will be disconnected. In this way, the receiving party avoids answering nuisance calls, obscene calls, wrong numbers or any other callers who do not have the correct security code.
A disadvantage associated with prior call screening devices is that they can be connected to only one telephone at a time. If a telephone system has more than one telephone, the user will have to return to the telephone connected to the device to answer an incoming call. Furthermore, prior call screening devices generate a ringing signal themselves and do not activate the ringers in the telephones. If a user is away from the call screening device, the user may not hear the ringing of the call screening device and thus would miss an authorized call. Moreover, these users must return to the call screening device in order to activate or deactivate the device.